• 터널과지하공간
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• 제12권4호
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• pp.268-276
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• 2002

In this study, a 3D coordinate measurement system equipped with a laser displacement meter for digitizing rock joint surface was established and the digitized data were used to calculate several roughness parameters. The parameters used in this study were micro avenge inclination $angle(i_{ave})$, average slope of joint $asperity(SL_{ ave})$, root mean square of $i-angle(i_{rms})$, standard deviation of height(SDH), standard deviation of $i-angle(SD_i)$, roughness profile $index(R_P)$, and fractal dimension(D). The relationships between the roughness parameters based on the digitzation of the surface profile were analyzed. Since the measured value varied according to the degree of reflection and the variation of colors at the measuring point, rock joint surface was painted in white to minimize the influence of the surface conditions. The comparison of the measured values and roughness parameters before and after painting revealed the better consequence from measurement on the painted surfaces. Also, effect of measuring interval was studied. As measured interval was increased, roughness parameters were exponentially decreased. The incremental sequence of degree of decrease was $SDH\; i_{ave},\; i_{rms},\; SD_i,\;and\; R_ p-1$. As a result of comparison of parameters from pin-type measurement system and laser type measurement system, all value of parameters were higher when laser-type measurement system was used, except SDH.

• Smart Structures and Systems
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• 제24권4호
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• pp.459-474
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• 2019

This study develops a novel recursive algorithm to significantly enhance the computation efficiency of a recently proposed stochastic subspace identification (SSI) methodology based on an alternative stabilization diagram. Exemplified by the measurements taken from the two investigated office buildings, it is first demonstrated that merely one sixth of computation time and one fifth of computer memory are required with the new recursive algorithm. Such a progress would enable the realization of on-line and almost real-time monitoring for these two steel framed structures. This recursive SSI algorithm is further applied to analyze 20 months of monitoring data and comprehensively assess the environmental effects. It is certified that the root-mean-square (RMS) response can be utilized as an excellent index to represent most of the environmental effects and its variation strongly correlates with that of the modal frequency. More detailed examination by comparing the monthly correlation coefficient discloses that larger variations in modal frequency induced by greater RMS responses would typically lead to a higher correlation.

• Composites Research
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• 제20권6호
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• pp.21-27
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• 2007

복합재 보강판에 영구히 부착된 배열 압전 능동 센서를 사용하여 저속 충격 손상을 탐지하였다. 압전 능동센서를 사용하여 구조에 램파를 전파시키기 위한 다양한 진단신호를 생성하였으며, 손상으로 인한 구조 진동의 특성 변화를 탐지하기 위하여 그 응답을 측정하였다. 이 신호 변화 특징을 한 개의 손상 지수로 표현하기 위하여 3가지 알고리즘-ADI(Active Damage Interrogation), TD RMS (Time Domain Root Mean Square), STFT(Short Time Fourier Transform) -이 검토되었다. 손상 탐지시험을 수행하여, 사용한 기법과 진단신호로 저속 충격으로 인한 두 개의 층간분리를 탐지하였으며, 그 위치를 추정하였다.

• 대한한방부인과학회지
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• 제18권3호
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• pp.192-202
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• 2005

Purpose : To investigate relation between Heart rate variability(HRV) and Kupperman's index. Methods : From 2004, 3, 15 to 2004, 4, 10, a total 18 female patients(age 40-61) was recruited. but 2 patients was excluded. one was under hormone raplacement therapy, the other was under drug treatment. We measured patient's HRV by SA-2000E(Medicore Co., Ltd., Korea), and they fulfilled kupperman's index and　qustionnaire.　Results : The mean age of patient was 50.13${\pm}$5.78 years. 6 of 16 patients was menopause, 12 of 16 patients had menstruation. half of 16 patients had a understanding about climacteric syndrome. Investigating relation between HRV and kupperman's index, kupperman's index had positive correlation with heart rate significantly. Kupperman's index had negative correlation with SDNN significantly. Kupperman's index had negative correlation with RMS-SD significantly. Conclusion : In this study, we presented relation between HRV and kupperman's index. Furthermore, large scale study is required.

• 한국소음진동공학회논문집
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• 제18권12호
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• pp.1217-1223
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• 2008

Vehicle vibration mostly originates from the road excitation and causes discomfort, fatigue and even injury to a driver. Vehicle ride comfort is one of the most important performance indices to achieve a high-quality vehicle design. Since design parameter variations inevitably result in the vehicle ride comfort variance, the variance characteristics should be analyzed in the early design stage of the vehicle. The vehicle ride comfort is often defined by an index which employs a weighted RMS value of the acceleration PSD of a seat position. The design solution is obtained through two steps in this study. An optimization problem to obtain a minimum ride comfort index is solved first. Then another optimization problem to obtain minimum variance of the ride comfort index is solved. For the optimization problems, the equations of motion and the sensitivity equations are derived basing on a 5-DOF vehicle model. The numerical results show that an optimal solution for the minimum ride comfort is not necessarily same as that of the minimum variance of the ride comfort.

• Journal of Positioning, Navigation, and Timing
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• 제13권1호
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• pp.63-73
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• 2024

NeQuick G is the ionosphere model utilized by Galileo single-frequency users to estimate the ionospheric delay on each user-satellite link. The model is characterized by the effective ionization level (Az) index, determined by a modified dip latitude (MODIP) and broadcast coefficients derived from daily global space weather observations. However, globally fitted Az coefficients may not accurately represent ionosphere within local area. This study introduces a method for regional ionospheric modeling that searches for locally optimized Az coefficients. This approach involves fitting TEC output from NeQuick G to TEC data collected from GNSS stations around Korea under various ionospheric conditions including different seasons and both low and high solar activity phases. The optimized Az coefficients enable calculation of the Az index at any position within a region of interest, accounting for the spatial variability of the Az index in a polynomial function of MODIP. The results reveal reduced TEC estimation errors, particularly during high solar activity, with a maximum reduction in the RMS error by 85.95%. This indicates that the proposed method for NeQuick G can effectively model various ionospheric conditions in local areas, offering potential applications in GNSS performance analyses for local areas by generating various ionospheric scenarios.

• 지구물리와물리탐사
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• 제19권2호
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• pp.67-75
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• 2016

저주파 (${\leq}5Hz$) 무작위 지진잡음의 시공간적 변화 특성을 밝히기 위하여, 국내 지표 가속도 관측소에서 2014년도 1년간 기록된 자료를 저주파(< 1 Hz)와 고주파(${\geq}1Hz$) 성분으로 분리한 후, 평균제곱근 진폭과 파워 스펙트럼 밀도를 계산하였다. 지진잡음은 주로 섬과 해안가 관측소에서 크게 기록되었으며, 고주파 성분은 내륙의 대도시 지역에서도 큰 진폭으로 관찰되었다. 고주파 성분은 야간시간대보다 주간시간대에 약 34% 크고, 일요일 및 명절연휴에는 평일보다 감소하여 인간 활동과 밀접한 연관이 있는 것으로 분석된다. 저주파 성분은 일변화 및 주간변화가 뚜렷하지 않지만, 겨울철에 크게 기록되어 계절별 차이를 보인다. 유의파고와도 높은 상관성을 보여 바다 등 주로 자연적 기작에 의해 발생된 것으로 해석된다. 또한 저주파 성분의 진폭은 태풍 중심까지의 거리에 따라 지수함수 형태로 감소하며, 지수 -0.76은 표면파뿐만 아니라 실체파 성분도 함께 포함되어 있을 가능성을 제시한다. 파워 스펙트럼 밀도의 정곡 주파수는 이중주파수 범위에 해당하는 0.34 Hz 정도로, 뚜렷한 시간적 변화를 보이지 않는다.

• 기록학연구
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• 제48호
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• pp.45-92
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• 2016

기업은 자신들의 경제 환경 사회적 영향 및 성과에 대해 설명책임의 수단으로 '지속가능성보고서'를 발간하고 있다. 법적 규제인 재무 공시와는 달리 '지속가능성' 보고는 비재무적 요소에 대한 기업들의 성과를 보고하는 것이기에 이에 대한 신뢰성은 기업에 의존할 수밖에 없다. 그러나 현재 발간되는 지속가능성보고서는 지표 데이터에 대한 증거나 출처를 포함할 수 없는 유형으로, 기업의 홍보 수단으로 여겨지는 경향이 있으며 신뢰성에 대한 의혹이 여러 차례 제기되고 있다. 이에 따라 본 연구에서는 업무에 대한 내용과 맥락이 담긴 기록으로 기업의 설명책임을 입증할 수 있도록 증거기반 설명책임에 대한 개념을 적용해 보았다. 증거기반 설명책임이란 행위에 대한 증거 기록을 생산 및 축적하고 이용가능한 정보로 관리하여 설명책임으로 활용하는 것이다. 국내 기업에서 발간한 지속가능성보고서의 지표데이터 유형과 영국 보다폰의 웹 기반 보고서 사례를 살펴보고, 업무 기록을 지표 데이터의 증거로 연결할 방안에 대해 연구해보았다. 이를 위해 필요한 기록을 증거로 확보할 수 있도록 기록의 생산체계를 재설계하였다. 업무 중 생산된 기록을 SR(Social Responsibility)설명책임정보로 취합 및 관리하고 이해관계자에게 제공할 수 있는 SR시스템(Social Responsibility System)과 기록관리시스템(RMS)의 연계 구축을 제안하였다. 또한 조직체계 및 규정을 통해 기업의 전문적인 기록관리 체계를 단계적으로 구축하고 관련 업무 담당자와의 협업을 통해 기업의 신뢰성 있는 설명책임을 지원할 수 있는 인프라 구축을 이야기했다.

• 한국전기전자재료학회논문지
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• 제30권4호
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• pp.199-203
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• 2017

$ZrO_2/PSS$ thin film with a high refractive index was fabricated on a glass substrate by a layer-by-layer self-assembly method. The surface morphology and thickness of the fabricated $ZrO_2/PSS$ thin films were measured as a function of the number of $(ZrO_2/PSS)n$. As the number of $(ZrO_2/PSS)n$ increased from n = 5 to n = 20, RMS roughness decreased from 29.01 nm to 8.368 nm. The $ZrO_2$ thin films exhibited high transmittance of 85% or more; and the 15-bilayer thin film exhibited the highest transmittance among the samples. The transmittance of the fabricated $(ZrO_2/PSS)_{15}$ thin film was ca. 90.8% in the visible range. The refractive index of the glass substrate coated by a $(ZrO_2/PSS)_{15}$ thin film with a thickness of 160 nm increased from ca. 1.52 to 1.74 at the 632 nm wavelength.

• 한국전문물리치료학회지
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• 제13권1호
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• pp.54-60
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• 2006

This study aimed to compare movement patterns of shoulder joints between the right and left symmetry in stroke patients and control subjects. This study proposes use of the voluntary response index (VRI) calculated from quantitative analysis of surface electromyographic (sEMG) and motion data recorded during voluntary movement as a feeding task. The VRI is comprised of two numeric values, one derived from the total muscle activity recorded for the voluntary motor task (magnitude), and the other from the sEMG distribution across the recorded muscles with the similarity index (SI). Five stroke patients and five age-matched healthy controls were recruited. Feeding motion was performed using the provided spoon five times with rests taken on a chair in between tasks. EMG data were digitized and analyzed on the basis of the root mean square (RMS) envelope of activity. The average amplitude of responses was calculated. Responsiveness and clinically meaningful levels of discrimination between stroke patients and control for EMG magnitude and SI were determined. The similarity index of the results from two successive examinations of both sides apart for stroke patients and control subjects were .86 and .95 in motion analysis and .84 and .99 in electromyographic analysis. The SI of sEMG data and motion data was significantly correlated in stroke patients. The data suggest that SI is a sensitive program for comparing and analyzing the symmetry of muscle activity and motion in both sides. This analysis method has a clinical value in grading muscular activity and movement impairment after brain injury.